Known types of flat panel displays include liquid crystal displays (LCD), plasma displays (PDP), organic light emitting displays (OLED), field effect displays (FED), eletrophoretic displays (EPD), and electrowetting displays (EWD).
Among these types of displays, the EWD expresses gradation in pixels by controlling movement of oil in water, which is an electrolyte. Since EWDs are shutter type displays that do not use a polarizing plate, an EWD has a high light transmittance and the gamma characteristics (measured by voltage) are linear. In addition, EWDs can be formed as a reflective type display or a transmission type display according to the environment of application. Reflective type displays may omit back light.
While EWDs use the same processes as those used in the processes for other types of flat panel displays such as, for example, LCDs, an additional filling process is required to fill water and oil in the display. Generally, for normal operation of EWDs, a layer below the oil must be a water repellent layer having a hydrophobic property. It is difficult to form a hydrophilic layer, like a partitioning layer, on the water repellent layer. To form a partitioning wall, the water repellent layer must be applied with a reactive ion etching (RIE) treatment. After forming a partitioning wall, oil is provided and then a thermal reflow process is applied so that the water repellent layer resumes hydrophobicity to operate the EWD.
As described above, a plurality of processes have to be conducted alternately to provide hydrophilicity and hydrophobicity, which results in a complicated process, increased time and increased cost. Furthermore, the water repellent layer after the thermal reflow process may fail to acquire sufficient hydrophobicity, which can lead to poor oil filling and deteriorated performance of the EWD.